This preview shows page 1. Sign up to view the full content.
Unformatted text preview: 7-55 continued with rearrangement-alkyl shift-ring expansion ��H2
C "....-A H2
� ("�-H�. O[ H H2C-C-H H20: I H H on 2° carbocation 5-membered ring HOORAY! H ('xCH/'RiI
.. MAJOR t -H 0 2 1° carbocation-terrible!-will rearrange; can't do hydride shift, must do alkyl shift ring expansion
= a gives bridgehead Hbstraction of adjacent alkene-violates Bredfs Rule t hydride shift this is an unstable carbocation even though it is 3°; bridgehead carbons cannot be sp 2 (planar-try to make a model), so this carbocation does a hydride shift to 2°, more stable carbocation
a this 2° carbocation loses an adjacent H to form an alkene; can't form at bridgehead (Bredt's Rule) only one other choice 158 ...
View Full Document
This note was uploaded on 02/27/2010 for the course CHEM 140 taught by Professor Wade during the Spring '10 term at Whitman.
- Spring '10